wht is ringing or girdling experiments?
Girdling, also called ring barking or ring barking, is the complete removal of a strip of bark (consisting of cork cambium, phloem, cambium and sometimes going into the xylem) from around the entire circumference of either a branch or trunk of a woody plant. Girdling results in the death of wood tissues above the damage
It was an experiment done to identify the tissue which transports food. In it , a layer of the bark containing the phloem layer is removed. In the absence of this tissue the part just above the removed portion becomes swollen as there was no transport of food downwards. This shows that phloem transports food to different parts of the plant.